Bidirectional single-line handshake with both devices driving the line in the same state for hand-off
US5734844A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 16, 1996 |
| Grant date | Mar 31, 1998 |
| Priority date | — |
| Expiry date | Feb 16, 2016 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02D10/00
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Bidirectional handshake protocol circuitry is provided for asserting and deasserting a signal across a single line between a first device and a second device. Only the first device is permitted to assert the signal on the single line; and only the second device is permitted to deassert the signal on the single line. The protocol is particularly useful between a chipset and a CPU where the chipset asserts a System Management Interrupt (SMI) and the CPU deasserts the interrupt to signal to the chipset that the service routine is complete. After assertion (or deassertion), there is an overlap or hand-off period whereby the single line is driven in the same direction by both devices. After a predetermined number of clock cycles, the device which asserted or deasserted the signal is tristated to await deassertion or assertion, respectively.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.